add BytesSize in pkg/units

Signed-off-by: Victor Vieux <vieux@docker.com>

pkg/units/size.go

@@ -32,18 +32,26 @@ var (
 	sizeRegex  = regexp.MustCompile(`^(\d+)([kKmMgGtTpP])?[bB]?$`)
 )
 
-var unitAbbrs = [...]string{"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"}
+var decimapAbbrs = []string{"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"}
+var binaryAbbrs = []string{"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"}
 
 // HumanSize returns a human-readable approximation of a size
 // using SI standard (eg. "44kB", "17MB")
 func HumanSize(size int64) string {
+	return intToString(float64(size), 1000.0, decimapAbbrs)
+}
+
+func BytesSize(size float64) string {
+	return intToString(size, 1024.0, binaryAbbrs)
+}
+
+func intToString(size, unit float64, _map []string) string {
 	i := 0
-	sizef := float64(size)
-	for sizef >= 1000.0 {
-		sizef = sizef / 1000.0
+	for size >= unit {
+		size = size / unit
 		i++
 	}
-	return fmt.Sprintf("%.4g %s", sizef, unitAbbrs[i])
+	return fmt.Sprintf("%.4g %s", size, _map[i])
 }
 
 // FromHumanSize returns an integer from a human-readable specification of a

pkg/units/size_test.go

@@ -7,6 +7,16 @@ import (
 	"testing"
 )
 
+func TestBytesSize(t *testing.T) {
+	assertEquals(t, "1 KiB", BytesSize(1024))
+	assertEquals(t, "1 MiB", BytesSize(1024*1024))
+	assertEquals(t, "1 MiB", BytesSize(1048576))
+	assertEquals(t, "2 MiB", BytesSize(2*MiB))
+	assertEquals(t, "3.42 GiB", BytesSize(3.42*GiB))
+	assertEquals(t, "5.372 TiB", BytesSize(5.372*TiB))
+	assertEquals(t, "2.22 PiB", BytesSize(2.22*PiB))
+}
+
 func TestHumanSize(t *testing.T) {
 	assertEquals(t, "1 kB", HumanSize(1000))
 	assertEquals(t, "1.024 kB", HumanSize(1024))